The Theory That Subaru's Memory Loss Is Connected to Return by Death
One of the most interesting fan theories surrounding Re:ZERO −Starting Life in Another World− Season 4 is that Subaru's memory problems may be more closely connected to Return by Death than they initially appear. At first, memory loss can look like another cruel problem thrown at Subaru, but the theory suggests that it could actually reveal something important about the supernatural mechanism that has allowed him to survive so many impossible situations.
Subaru's greatest advantage has never simply been Return by Death itself. His real advantage is the information he carries from previous timelines. Every failed attempt gives him knowledge about enemies, locations, relationships and possible solutions. Over time, those experiences become part of his personality. He is essentially building an enormous mental record that nobody else can access.
This creates an interesting question: what would happen if Subaru could no longer access those memories?
The fan theory suggests that Return by Death might somehow be involved. Perhaps the ability does more than return Subaru's body to an earlier point. Maybe there is a deeper connection between his supernatural power and the memories he accumulates from previous loops.
If that were true, Subaru's memories would not merely be ordinary memories. They could be evidence that something unusual is happening to his existence every time Return by Death activates.
Another possibility is that the memory problem is a deliberate way of showing the limits of Subaru's ability. Return by Death appears incredibly powerful because Subaru can repeatedly learn from failure, but perhaps the story has always contained an invisible cost. The more Subaru relies on repeated timelines, the more complicated his relationship with his own memories could become.
This theory also fits one of the most important themes of Re:ZERO: identity.
Who is Subaru if you remove the experiences that shaped him? His courage, relationships, regrets and determination are all connected to things that happened during previous loops. A Subaru who forgets those experiences could technically be the same person, but emotionally and psychologically he might become someone very different.
That makes the memory problem potentially much more important than simply "Subaru forgot something."
It could be asking whether a person's identity is defined by their memories or by something deeper.
The theory remains unconfirmed, but Season 4's focus on memory and identity makes it an especially interesting possibility. If future events reveal that Subaru's memories and Return by Death are connected, something that initially looked like another obstacle could become a major clue about how Subaru's mysterious ability actually works.